DeepControl.Commutative

This module is made of Traversable, distilling most function names polluted with action kind of concepts into crystalized(static) ones. Another reason I put this module is for the case if GHC would parse ((->) r) as a data constructor someday.

The Commutative class

class Functor c => Commutative c where

Methods

commute :: Applicative f => c (f a) -> f (c a)

This method is the same for sequenceA just except the name. The only difference is the name "commute", that is to say from which no action kind of concepts smell.

Instances

Commutative []

Commutative Maybe

Commutative (Either a)

Commutative ((,) a)

Commutative (Const m)

Utility functions

cmap :: (Applicative f, Commutative c) => (a -> f b) -> c a -> f (c b)

Do fmap f then commute, the same for traverse.

cfor :: (Applicative f, Commutative c) => c a -> (a -> f b) -> f (c b)

The auguments-flipped function for cmap, the same for for.

General definitions for superclass methods

fmapDefault :: Commutative t => (a -> b) -> t a -> t b

This function may be used as a value for fmap in a Functor instance, provided that commute is defined. (Using fmapDefault with a Commutative instance will result in infinite recursion.)

foldMapDefault :: (Commutative t, Monoid m) => (a -> m) -> t a -> m

This function may be used as a value for foldMap in a Foldable instance.